/// <summary>Returns new list in reverse order.</summary>
/// <typeparam name="T">List item type</typeparam> <param name="source">List to reverse.</param>
/// <returns>New list. If list consist on single element, then the same list.</returns>
public static ImList <T> Reverse <T>(this ImList <T> source)
{
if (source.IsEmpty || source.Tail.IsEmpty)
{
return(source);
}
return(source.To(ImList <T> .Empty, (it, _) => _.Prep(it)));
}
/// <summary>Copies list to array.</summary>
/// <param name="source">list to convert.</param>
/// <returns>Array with list items.</returns>
public static T[] ToArray <T>(this ImList <T> source)
{
if (source.IsEmpty)
{
return(new T[0]);
}
if (source.Tail.IsEmpty)
{
return new[] { source.Head }
}
;
return(source.Enumerate().ToArray());
}
}
/// <summary>Form of fold function with element index for convenience.</summary>
/// <typeparam name="T">Type of list item.</typeparam>
/// <typeparam name="R">Type of result.</typeparam>
/// <param name="source">List to fold.</param>
/// <param name="initialValue">From were to start.</param>
/// <param name="collect">Collects list item into result</param>
/// <returns>Return result or <paramref name="initialValue"/> for empty list.</returns>
public static R To <T, R>(this ImList <T> source, R initialValue, Func <T, int, R, R> collect)
{
if (source.IsEmpty)
{
return(initialValue);
}
var value = initialValue;
for (var i = 0; !source.IsEmpty; source = source.Tail)
{
value = collect(source.Head, i++, value);
}
return(value);
}
/// <summary>Maps the items from the first list to the result list with item index.</summary>
/// <typeparam name="T">source item type.</typeparam>
/// <typeparam name="R">result item type.</typeparam>
/// <param name="source">input list.</param> <param name="map">converter func.</param>
/// <returns>result list.</returns>
public static ImList <R> Map <T, R>(this ImList <T> source, Func <T, int, R> map)
{
return(source.To(ImList <R> .Empty, (it, i, _) => _.Prep(map(it, i))).Reverse());
}
private ImList(T head, ImList <T> tail)
{
Head = head;
Tail = tail;
}
